California Water Commission

Pacheco Reservoir Expansion Unique Opportunity for Fisheries Recovery, Flood Risk Reduction and Emergency Water Supply

December 13, 2017

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Pacheco Pass Water

District

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Pacheco Creek

Project Partners

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PachecoExpansion

Existing PachecoReservoir

Project Location

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The Project Delivers a High Percentage of Public Benefits

Ecosystem Improvement

$722M50%

EmergencyResponse$455M

31%

Water Supply/Quality$282M

19% 2.43Public

Benefit Ratio

81%Public Benefits

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The Partners Seek to Address Five Big Challenges

Improve Resiliency and Emergency Water Supply

Eliminate Water QualityIssues in San Luis Reservoir

Reduce Flooding to Disadvantaged Communities

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90% population decline in Pajarowatershed from 1960s to 1990s

90% of Delta watershed wetlands have disappeared

66% chance of Delta earthquake in next 50 years; 45% of water supply imported from Delta

Water quality issues during summer months in 57% of years

Extensive flooding even for frequent/small events; 20-year flood in 2017 (pictured)

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Improve theDelta

Restore Federally Threatened Fish

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The Reservoir Expansion will Provide Public Solutions

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Enables Federally Threatened Steelhead Recovery

The project will improve conditions in watershed critical to recovery• Improves water flow in Pacheco Creek in

all hydrologic conditions• Larger cold water pool improves

temperature in Pacheco Creek• Increases SCCC Steelhead cohort score

between 162% (2030) and 178% (2070)• Enables growth of an independent

population in the Pajaro River watershed

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0

5

10

15

20

25

Wet AboveNormal

BelowNormal

Dry Critical

Without Project With Project

Coh

ort S

core

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Dry Pacheco Creek - August 2014 1.3 cfs flow - July 2016 Pacheco Creek will have enhanced flow

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Enhances Bay-DeltaEcosystem

Increased water supplies to Delta watershed refuges• Dedicates irrigation to wetlands

in below-normal water years• Increases food supply for

migrating Pacific Flyway waterfowl in the fall and winter

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"California's last remaining 5% of wetlands are found on wildlife refuges in the Central Valley and are critical to the health of the millions of migratory birds using the pacific flyway each year. The Pacheco reservoir expansion project proposes to provide thousands of acre feet to these refugesin below normal water years when water supplies south of the delta are scarce and highly expensive to help maintain thousands of acres of this critical public trust.”

Ric Ortega, Grassland Water and Resource Conservation Districts

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Reduces Flooding in Disadvantaged Communities

The project will protect disadvantaged and vulnerable communities against flooding

• Decreases flood flows from North Fork Pacheco Creek by up to 61%

• Reduces downstream 100-year flood flows by up to 4,700 cfs

• With the new reservoir, 2017 flood flows in North Fork Pacheco Creek would have been fully contained

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Pictured above: Hollister 2014 flooding

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Eliminates San Luis Low Point Water Quality Issues

The project reduces operational constraints at San Luis Reservoir Prevents 73 months of impaired water quality deliveries (2030) and 109 months (2070) by: • Delivering CVP supplies to the Pacheco

Reservoir earlier in the season • Capturing Pacheco watershed supplies in the

expanded reservoir

• Using the Pacheco Reservoir as a blending source when needed.

Thus, project operations will avoid spikes in taste and odor measuring 10 times normal levels, which cause problems in today’s domestic supply

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Algae Bloom in San Luis Reservoir

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Emergency Water Supply

The project will provide dedicated emergency water supply• Increases emergency water supply in

2030 and 2070 by 82,000 and 87,000 acre-feet

• Increases local surface storage capacity by 90%

• Mitigates risk of Delta export outages and imported water conveyance outages

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Delta levee failure,

Jones Tract

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The Project will Enhance Water Supply for Agriculture and M&I

The project will reduce drought risk to agricultural and M&I water users• Increases water supply by up to 20,000

acre-feet in dry years • Improves groundwater conditions to

agricultural customers• Materially contributes to sustainable

groundwater management goals in four basins

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The Environmental Benefits are Compelling

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High Relative Environmental Value --Addresses 11 of 16 Ecosystem Priorities

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✔ P 1Provide cold water at times and locations to increase the survival of salmonid eggs and fry.

✔ P 2Provide flows to improve habitat conditions for in-river rearing and downstream migration of juvenile salmonids.

✔ P 3Maintain flows and appropriate ramping rates at times and locations that will minimize dewatering of salmonid redds and prevent stranding of juvenile salmonids in side channel habitat

✔ P 4 Improve ecosystem water quality. Dissolved oxygen, turbidity, coliform

✔ P 5Provide flows that increase dissolved oxygen and lower water temperatures to support anadromous fish passage

✔ P 8Maintain or restore groundwater and surface water interconnection to support instream benefits and groundwater dependent ecosystems.

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P 6Increase attraction flows during upstream migration to reduce straying of anadromous species into non-natal tributaries

P 7Increase Delta outflow to provide low salinity habitat for Delta smelt, longfin smelt, and other estuarine fishes in the Delta, Suisun Bay, and Suisun Marsh

P 10Enhance the frequency, magnitude, and duration of floodplain inundation to enhance primary and secondary productivity and the growth and survival of fish

P 13 Remediate unscreened or poorly screened diversions to reduce entrainment of fish

P 15Develop and implement invasive species management plans utilizing techniques that are supported by best available science to enhance habitat and increase the survival of native species

✔ P 9

Enhance flow regimes or groundwater conditions to improve the quantity and quality of riparian and floodplain habitats for aquatic and terrestrial species.

✔ P 11Enhance the temporal and spatial distribution and diversity of habitats to support all life stages of fish and wildlife species

✔ P 12Enhance access to fish spawning, rearing, and holding habitat by eliminating barriers to migration

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Provide water to enhance seasonal wetlands, permanent wetlands, and riparian habitat for aquatic and terrestrial species on State and Federal wildlife refuges and on other public and private lands

✔ P 16Enhance habitat for native species that have commercial, recreational, scientific, or educational uses

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High Resiliency – Low Risk

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Provides System Wide Integration

Refuge deliveries

Modify delivery pattern to avoid water quality issues

Pacheco Creek flows

M&I and Ag water supply

Delta

Expanded Pacheco Reservoir

San LuisReservoir

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Water supply for Central Valley Ag and Los Angeles

How the Project will be Operated

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Drought All Public Benefits Maintained/Increased

The Project Performs Well in an Uncertain Future

Public Benefit

Project Benefits Performance Under Uncertainty Scenarios

Ecosystem Improvement -Delta Watershed (acre-feet)

Maintained in all uncertainty scenarios

Ecosystem Improvement -Pacheco Creek(% increase in Cohort Score)

Maintained or improved in all uncertainty scenarios

Emergency Response (acre-feet)

Improved in all uncertainty scenarios

Uncertainty ScenariosAll Public Benefits Maintained/Increased

Public Benefit

Project Benefits Under Drought

Ecosystem Improvement -Pacheco Creek(% increase in Cohort Score)

Significantly improvedperformance during drought

Emergency Response (acre-feet)

Maintained during drought

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Broad Statewide Support

Supported by:• Business• Agriculture• Disadvantaged community

advocates• Labor groups • Cities/Counties• Water agencies• Elected officials• Natural resources groups

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Successful Implementation Builds on Track Record and Financial StrengthEstablished Operator: Santa Clara Valley Water District• 800 Employees• Manages 10 existing dams/reservoirs,

constructed beginning in the 1930’s• Provides water supply, flood protection, and

stewardship of streams

• Serves 1.9 million people in Silicon Valley• Demonstrates excellent financial stewardship in

funding its capital projects• DSOD letter regarding Pacheco: “We are

pleased that SCVWD with its expertise and resources are pursuing this Enlargement Project”

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Pictured above: Lexington Reservoir

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Project Partners have Technical and Financial Ability to Meet all WSIP Milestones

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November 2021

Draft EIS/EIR

October 2023

ROD/NOD

January 2024

Final Commission Consideration

Permits February 2024

Construction Contract Award

May 2024

Construction Mobilization

Late Spring 2025

Public Benefits Begin to Accrue

September 2028

Start of Project Operations

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Recap: The Project will Achieve Five Important Public Benefits

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Enhances steelhead habitat

Provides emergency supply

Resolves water quality problem

Supports disadvantaged communities

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Supplies Delta refuges

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• Existing Dam/Reservoir6,000 acre-foot reservoir

100-foot-tall earth embankment dam

Concrete spillway

ExistingPacheco Reservoir Facilities

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Proposed Pacheco Reservoir Facilities • Expanded Dam/Reservoir

140,000 acre-foot reservoir

New 319-foot earth embankment dam

Concrete spillway

• Conveyance between Pacheco Conduit and expanded reservoir

1-Mile tunnel/pipeline

Pump station

Selective level inlet/outlet structure within reservoir

• New regulating tank near San Luis Reservoir

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Affected Water Facilities

Existing Pacheco Reservoir

and North Fork Dam San Luis

Reservoir and CVP San Felipe

Division Facilities

Federal/ State/Local

conveyance facilities to

deliver refuge supplies

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Federal/State/Regional Operational Flexibility

Improves Federal, State, and Regional Operational FlexibilityCombined Pacheco-San Luis Reservoirs

• Reduced operational constraints and increase effective storage

• Improved water quality

• Improved transfer and exchange opportunities

• Reduced Delta pumping during critical biological periods

• Increased flexibility for refuge deliveries

• Increased flexibility for Semitropicstorage and conveyance facilities

• Increased emergency supplies for other regional users (non-project partners)

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New Facilities will Replace a Damaged 78-year-old InfrastructureWithout repairs satisfactory to DSOD, the reservoir will be drained and downstream fisheries will be impactedReplacement will:• Reduce risks to human health and safety

and improve fisheries habitat• Maintain groundwater recharge benefits

for Pacheco Pass Water District

DSOD letter regarding Pacheco: “We are pleased that SCVWD with its expertise and resources are pursuing this Enlargement Project”

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Damaged Spillway of

Existing Dam

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Respecting Native American ResourcesObjective: To preserve and guard the history and cultural resources of California Native American tribes• Coordinating with nine tribes on a Tribal

Consultation and Outreach Plan

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DroughtAll Public Benefits Maintained/Increased

The Project Performs well in an Uncertain Future

PublicBenefit Base Uncertainty

Scenarios

Project BenefitsPerformance Under

Uncertainty ScenariosEcosystem Improvement -Delta Watershed (acre-feet)

2,000 2,000 Maintained in all uncertainty scenarios

Ecosystem Improvement -Pacheco Creek(% increase in Cohort Score)

178% 178% to 278% Maintained or improved in all uncertainty scenarios

Emergency Response (acre-feet)

82,000 83,000 to 107,000

Improved in all uncertainty scenarios

Uncertainty ScenariosAll Public Benefits Maintained/Increased

PublicBenefit Base Drought

PeriodProject BenefitsUnder Drought

Ecosystem Improvement -Pacheco Creek(% increase in Cohort Score)

178% 586%

Significantly improved

performance during drought

Emergency Response (acre-feet) 82,000

61,000 to 111,000; average

81,000

Maintained during drought

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The Case for Pacheco Reservoir Expansion

Project Scope• Funding ask: $484.5 million• Resolves or measurably contributes to

high-stakes challenges in Bay-Delta watershed

• Serves both urban and rural communities

Benefits• Enhances Bay-Delta watershed ecosystem,

including vital refuges and wetlands• Enables federally threatened

species recovery• Increases emergency water supply to

Silicon Valley economic hub• Provides critical flood control by reducing

Pacheco Reservoir releases • Boosts M&I water supply during

drought periods• Eliminates San Luis low point

water quality issues• Replaces damaged dam

with new facilities

High Resiliency, Low Risk• Improves federal, state,

and local operational flexibility

• All public benefits maintained or increased in the face of uncertainty

• Established partner and broad support ensure successful implementation

Getting Started• Positioned to meet all

WSIP milestones

Environmental Value• Addresses 11 of 16 Relative

Environmental Value Priorities

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